1. Field of the Invention
A ski sledge comprising a swiveling front ski with steering means, two essentially mutually parallel rear skis connected to the sledge with a parallelogram arrangement, and a seat connected via one or more rods to the steering means according to the preamble of claim 1.
2. Description of the Related Art
Turning systems for such ski sledges are known from prior art, having a front ski and to rear skis, where the front ski can be swiveled.
In addition, prior art includes sledges with two longitudinal runners, where the runners can be turned synchronously by means of a steering wheel.
From Norwegian patent 135699 there is known a steerable sledge of the above type, which sledge includes a seating portion that, at a rear part of the sledge, is connected to a pair of main runners via support stays supported rotatably about transverse axes in the seating portion and main runners, respectively, together with a central steering runner rotatably supported in the front part of the seating portion, characterized in that the seating portion, in a front part of the sledge, is rotatably supported about a longitudinal central axis, in a raised transverse joint front portion rigidly mounted to the two main runners.
From U.S. Pat. No. 6,068,269 there is known a sledge consisting of two or three runners or skis, where the runners or skis may be pressed against the underlying surface independently of each other, thereby achieving a turning effect.
From U.S. Pat. No. 6,279,925 there is known a sledge comprising two runners or skis, including a control mechanisms that allows the skies to be moved at different levels.
From U.S. Pat. No. 4,796,902 there is known a sledge having a total of four runners or skis, which includes a mechanism that allows two of the skis to be moved with respect to each other at the same time.
From U.S. Pat. No. 6,474,662 there is known a steering mechanism for a snow scooter, in which each of the front steering skis is connected to the actual snow scooter by means of steering tie rods.
From DE-A1 2525790 there is known a ski sledge, where the two rear skies are fastened to the sledge itself by means of a parallelogram construction. According to this publication, use is made of an upright parallelogram which is fastened to lateral rotatably attachments.
From DE-A1 there is known a.o. two embodiments of a parallelogram construction for use with a sledge. The parallelogram according to this publication has similarities with the parallelogram according to present invention, since it is centrally mounted. However, according to this publication, use is made of a standing parallelogram and not a parallelogram angled in a forward direction in connection with a damper device and rotatable joints.
From U.S. Pat. No. 5,242,176 there is known a salvage sledge (ski sledge) adapted for towing behind snow vehicle, which uses a parallelogram to achieve a dampening effect. Each of the rear skies are independently attached to the sledge chassis by use of a separate parallelogram for each ski. The parallelogram construction according to this publication is situated in a plane which seems to be approximately parallel to the longitudinal axis of the sledge (and the direction of movement). This implies that the parallelograms do not allow any significant angling of the skies in relation to the main chassis of the sledge.
DE-A1 2533117 describes a sledge/snowracer with a parallelogram device connecting the two rear skies with the chassis of the sledge (cf. FIGS. 8 and 9). This parallelogram device only comprises one parallelogram.
U.S. Pat. No. 6,474,662 describes a damper device for a snow scooter based on a parallelogram. This parallelogram is connected to the chassis of the vehicle to achieve dampening effect. The parallelogram is not centrally mounted nor positioned obliquely with a damper.
SE-C2 also describes a damper/turning-concept for a snow scooter, which make use of dampers and a parallelogram connected to each ski.
From DE-A1 there is know a ski sledge comprising to substantially parallel skies, each of which is connected to the seat of the sledge by means of two parallelograms, mounted at the front and the rear, respectively. This solution does not make use of a centrally mounted, forward angled parallelogram device in combination with a damper device.
Various other means of steering sledges are known, inter alia, from the following publications:    EP 0 117 901    EP 0 005 485    DE 196 02447 C2    DE off. schrift 24 09 309    DE off. schrift 198 45 634 A1    DE off. Schrift 39 35 938 A1    U.S. Pat. No. 5,335,925    U.S. Pat. No. 6,530,582, and    U.S. Pat. No. 4,334,691
A disadvantage of these prior art solutions is that they only give limited control when turning at high speeds. The problem is that these known solutions do not allow sufficient weight transfer to enable one to resist the centrifugal forces and the force of gravity affecting the sledge and the driver when turning at high speeds. Furthermore, none of the known solutions are adapted for driving while standing up.
There is also known a number of so-called snowbikes/skibikes, which have two skis arranged after each other and which, as a consequence, will not provide the required balance for long jumps and great heights in the halfpipe/quarterpipe.